Electrical Conduction in Chalcogenide Glasses. Applicability of the Meyer-Neldel Rule

The dependence of the pre-exponential factor (σ0) on the activation energy (ΔE) is investigated for SeTe, SeTeM, GeSe, and GeSeM glassy alloys where M is a metal. An approximate linear dependence of In σ0 on ΔE is observed in SeTe and SeTeM systems with good quantitative agreement between the expected and calculated σ0 values using Meyer-Neldel rule. Linear dependence of In σ0 on ΔE in case of amorphous materials indicates that the conduction band tails a finite energy distance towards the valence band and a Fermi level which is controlled by fixed dominant hole levels deeper in the gap.